I got my oil sump replaced a few weeks ago, and went to top up the oil today, but can't get the cap open! It's jammed shut.
Kind of embarassed to ask here, as it seems such an easy question, but I've tried with all my might and can't budge it! Any ideas? Would WD40 or similar make any difference?
You need to get more leverage on it, but being lower than the engine cover that's not possible.
WD40 won't hel as you can't get the fluid to where it sticks.
First option is a glove with good grip.
I've had to use an adjustable wrench in the past: place a cloth over the cap and drop the "fingers" of the wrench down at the sides and tighten gently until it touches. Then give it a couple of gentle tweaks. The extra leverage usually does the trick.